Flaw detector for knitting machines and the like



FZLAW DETECTOR FOR KNITTING MACHINES AND THE LIKE Filed Feb. 9, 1952 4 Sheets-Sheet 1 INVENTOR. HENRY E. PEEK ATTORNEY f H. E. PECK Nov. 23, 1954 FLAW DETECTOR FOR KNITTING MACHINES AND THE LIKE 4 Sheets$heet 2 4 INVENTOR.

HENRY E. PECK ATTORNEY Filed Feb. 9, 1952 H. E. PEC K Nov. 23, 1954 FLAW DETECTOR FOR KNITTING MACHINES AND THE LIKE Filed Feb. 9, 1952 4 Sheets-Shae t 3 INVENTOR. HENRY 2 PEGK A 7'TORIVE'Y H. E. PECK Nov. 23, 1954 FLAW DETECTOR FOR KNITTING MACHINES AND THE LIKE 4 Sheets-Sheet 4 Filed Feb. 9. 1952 Q Q mt INVENTOR. HENRY E PEG/f A? TTORWEY United States Patent Ofiice 2159431 1 Patented Nov. 23, 1954 FLAW DETECTOR FUR KNITTING MACHINES AND THE LIKE Henry E. Peck, Fairport, N. Y., assignor of one-third to Herbert Scllatzki, one-third to Else Schatzki, and onethirtl to Lemuel W. Eisenwinter, all of Bristol, Conn.

Application February 9, 1952, Serial No. 270,787

20 Claims. (Cl. 66-166) The present invention relates to a stop-motion device for knitting machines and the like, and more particularly to a device for detecting flaws in the fabric being knitted, and which is operative, upon detection of a flaw, either to stop the machine or to give a warning signal. The invention is particularly adapted for use on machines for knitting tricot.

Conventionally tricot cloth is knit 168 inches wide; and conventionally the knitting machines are adjusted to knit a length of fabric 8 inches long in a minute. Sometimes the needles drop threads. If the operator fails to observe the dropping of the threads, in one minute there are 8 inches of material 168 inches wide having a flaw in it; in five minutes there would be 40 inches of material 168 inches wide with a flaw; the machine will continue to produce defective fabric until the cause of the flaw is corrected.

To avoid loss, it has heretofore been proposed to use various devices, including photo-electric cells, to detect promptly any flaws in the knitting. The photo-electric cells are located close to the line at which the fabric is being knitted, and light coming from the fabric is directed i into the cells, so that variation in the amount of light will cause a photo-electric cell to operate a stop motion mechanism. it has been found, however, that the photoelectric cell is too sensitive. It will stop a machine even because of a slight variation in color of the knitted fabric. Other flaw detectors have also proven unsatisfactory for one reason or another.

The primary objects of the present invention are to provide a flaw detector which can be used close to the line at which the fabric is being knitted, and which will be simple in construction and operation, relatively inexpensive, and practical, serving to stop the machine and give a signal only when stitches are dropped, or a thin place in the fabric is encountered.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims.

in the drawings:

Fig. l is a more or less diagrammatic side elevation of a conventional knitting machine having thereon a flaw detector apparatus constructed according to one embodiment of the present invention;

Fig. 2 is a fragmentary plan view of the machine further illustrating the detector apparatus and its mounting;

Fig. 3 is a fragmentary plan view of the detector apparatus on a greatly enlarged scale;

Fig. 4 is a section through this detector apparatus taken on the line 44 of Fig. 3 and looking in the direction of the arrows;

Fig. 5 isa part side elevation, part section taken at right angles to Fig; 3, further illustrating: a part of this detector mechanism;

Pig. 6 is a fragmentary section showing in continuation of Fig. 5 other parts of the detector mechanism to the right of those shown in Fig. 5;

Fig. 7 is a view on a further enlarged scale showing the construction of one of the detectors;

Pig. 8 is a section on the line. 88 of Fig. 7 looking in the direction of thearrows;

Fig. 9' is a plan view of the parts shown in Fig. 7, with the housing further broken away and shown in section;

Fig.v 10 is a. cross-section through the housing at right angles to Fig. 9;

Fig. 11 is a cross-section through the screw and nut for traversing the detector apparatus back and forth across the Width of the fabric;

Fig. 12 is a view similar to Fig. 5 illustrating a modification of the invention in which fluid pressure, instead of a screw and nut, is used to move the detector nozzles in scanning relation across the width of the cloth;

Fig. 13 is a fragmentary side elevation of a detector apparatus made according to a further embodiment of the invention;

Fig. 14 is a transverse section through this detector mechanism;

Fig. 15 is a section on the line 15-15 of Fig. 14, looking in the direction of the arrows; 15Fig. 16 is a fragmentary section at right angles to Fig.

Fig. 17 is a perspective view of a nozzle made according to one embodiment of the present invention with the cap therefor removed;

Fig. 18 is a perspective view of the cap and showing the nozzle in phantom;

Fig. 19 is a fragmentary plan view on a reduced scale showing a pair of these detectors in position; and

Fig. 20 is a diagram illustrating one way in which the machine may be wired so that the flaw detectors effect stoppage of the machine upon detection of a flaw in the fabric.

A detector made according to the present invention comprises a nozzle over the mouth of which the knitted fabric is fed as the fabric moves from the needles to the wind-up roll of the knitting machine. The nozzle is traversed back and forth across the width of the fabric close to the line at which the fabric is being knitted. Compressed air of very low pressure, in the neighborhood of one pound per square inch, is delivered to the nozzle so that air flows at a given rate through the minute interstices of the fabric. As long as the fabric traversing the nozzle is whole, this rate of flow continues. If a thin spot or hole (due, for instance, to a dropped stitch) is encountered at any point in the fabric, however, the air will flow from the nozzle at an increased rate, creating. a change in pressure. Through suitable means this is used to stop the machine and to give a warning signal.

The device of the present invention may be used upon any conventional tricot or fiat knitting. machine. In Fig. 1, 20 denotes the side frame of such a machine, 21 and 22 are the spools from which the threads are supplied, 24 is an idler or guide roll and 23 is the take-up roll on which the knitted fabric is wound. At a convenient point on the machine, somewhere along the course of travel of the knitted fabric from the needles to the takeup roll 23, preferably as close to the needles as possible so as to detect as quickly as possible any flaws in the knitted fabric, there is positioned a detector apparatus denoted generally at 25, made according to this invention.

In the embodiment of the invention illustrated in Figs. 3- to 10 inclusive, the detector mechanism comprises a plurality of sensing heads 26 (Figs. 5 and 6) that are secured in any suitable manner, as by means of welding, on top of a tubular duct 28 that is rectangular in cross section (Fig. 8). The sensing heads together with the duct are adapted to be reciprocated to move the sensing heads in scanning relation across the width of the knitted material F. There may be fifteen sensing heads 26 provided in a machine, spaced approximately on 10 inch centers and all secured on top of the duct 28, so that with a ten-inch stroke of the duct, the whole of the width of the fabric can be scanned at a single stroke of the sensing heads.

Each sensing head comprises a nozzle 30 which is threaded into the head 26 and secured therein by a nut 3-1 (Fig. 8).. The nozzles 30 have a plurality of fine holes 32 (Fig. 9) therein which are preferably aligned in the driection. of linear travel of the fabric P so that the. nozzle senses a suificient length of fabric at a time to insure that all of the length of fabric formed between successive strokes of the nozzle will be sensed.

T he duct 28 and the sensing heads 30 attached thereto are reciprocated by rotation of a sleeve 35 (Fig. 5 which is. held against axial movement. There is a sprocket 36 secured to this sleeve which may be driven by a chain from a convenient, continuously rotating part of the knitting machine. The sleeve 35 is journaled by means of an antifriction bearing 44 upon a pillow block or other support 45 in the machine. The sleeve is held against axial movement relative to support 45 by a nut 47, which threads on the sleeve and which engages the inner race of bearing 44, and by a set-screw 48, which engages sleeve 35 and locks the nut 47 against rotation relative tosleeve 35.

Mounted in a pocket in the sleeve 35 is a segmental nut member 37. This nut member is held in the pocket in sleeve 35 by a .ring 39 that is fastened to sleeve 35 by a screw 43. The segmental nut member 37 has a thin web portion 38 (Figs. 5 and 11) that is adapted to engage with threads 41 and 42 formed on the periphery of a tubular rod 40. The threads 41 and 42 are of opposite hand and intersect one another.

As the sleeve is rotated by the sprocket 36, nut segment 38 will by engagement with one or other of the threads 41 and 42 cause the tube to move axially within the sleeve. The nut will travel to one end of a thread of one hand and then reverse the tubular rod 40, and cause that rod to travel in the opposite direction until the nut comes to the end of the opposite hand thread, when reversal occurs again. Thus as sleeve 35 rotates, the sensing nozzles will be traversed continuously back and forth across the fabric as it leaves the knitting needles.

Compressed air under very low pressure, of say eight to twelve pounds per square inch, is supplied to the tube 40 through an air hose which is connected by a conventional coupling 51 with one end of the tube 40. The tube 40 is connected at its other end with duct or manifold 28 by means of a block 55 which is welded or otherwise secured on top of the left hand end of the duct 28 and which seats upon the right hand end portion of the tube 40. This portion of the tube is of reduced diameter. The block 55 is secured to rod or tube 40 by a bolt 56 that passes through the block and threads into the tube. Gaskets 57 and 58 are provided to prevent leakage. There is a duct 60 provided in the block 55 which communicates at one end through an opening 61 with the interior of the duct 28 and which communicates at its other end with the bore of tube 40 through an opening cut into the reduced end portion of that tube.

Rollers 65, which are journaled on brackets 66 that project upwardly from the duct 28 (Figs. 5 and 10), serve to guide and carry the duct and the sensing heads in their reciprocating movements. These rollers ride on ways 67 (Figs. 8, 9, and 10) that are welded or secured to the insides of two plates 68 and 69 (Fig. 8) that form a housing within which the sensing heads travel. These plates 68 and 69 are bent toward one another at their upper free ends, as clearly shown in Fig. 8, but they are spaced apart at their upper ends sufficiently for the nozzles 30 to protrude through the space provided between them. At

their lower ends these plates are welded to a bar 70 that is secured to the frame of the machine.

The sensing heads 26 are all alike. Each has a duct 71 in it that communicates at its lower end (Fig. 8) with the duct 28 through a hole 72 in the upper wall of the duct 28. The duct 71 communicates at its upper end with a right angular duct 73, that, in turn, communicates with a duct 75 that extends at right angles to the duct 73 and parallel to a duct 71. This, in turn, communicates with a duct 77 that is drilled in each sensing head 26 to extend in the direction of travel of the duct 28. Each duct 77 leads into a bellows 80 (Figs. 7 and 9).

This bellows is of conventional construction. It is closed at one end by the sensing head 26 and at its opposite end it carries a plate 81 to which is fixed a rod 82. Pivotally connected at 83 to the rod 82 is an arm 84. This arm is pivotally connected at 85 with an insulating block 86. Arm 85 carries a contact member 87 which is adapted to engage a contact member 88 carried by a rightangular strap 89 that is fastened to plate 90. The distance between the arms 84 and 89 can be adjusted by adjustment of a tapered screw 92 (Figs. 7 and 9) that threads into the block 86 at the split 94 therein.

Each of the terminals 87 and 88 is connected in suitable fashion to one side of an electrical line that leads preferably through an amplifier 91 (Fig. 20) to a solenoid or similar device 93 for operating a normally closed switch 98 either in the circuit to the main drive motor 187 of the machine or in the circuit to a signal. The electrical connections may be through wires 95 (Fig. 6), the several pairs of terminals 87, 88 of the different sensing heads being connected in parallel with the two wires 95. As illustrated diagrammatically in Fig. 20, the switch 98 is in series with a conventional motor starter 108. The main lines to the motor are denoted at 109. 115 is a conventional manually operable stop.

The amount of air pressure at the nozzle 30 can be adjusted by adjustment of a needle valve 100 (Fig. 8) which threads into nuts 101 and 102 that in turn thread into the head 26. The needle valve is adjusted in accordance with the type of fabric being knitted and also so that the orifice or opening between ducts 73 and 75 will be smaller in area than the total area of the orifices 32 (Fig. 9) in the nozzle. Thus, when a thin spot or flaw in the fabric is encountered, the air fiows out of the orifices 32 faster than it can be replenished, thus causing a pressure drop.

The fabric F, after it has been knitted by the needles of the machine, is fed over the plates 68 and 69 and the nozzles 30, as shown in Fig. 8, and the nozzles are traversed across the width of the fabric (Fig. 7). As long as there is no break in the fabric the fabric will limit the rate of flow of air from the nozzles, and the air pressure in the several bellows 80 will hold the several contacts 87 away from the associated electrical contacts 88. If there is a thin spot in the cloth or if needles drop a stitch, however, one of the fiften nozzles 30 in their continuous scanning movement across the continuously moving fabric will encounter the flaw. Immediately the air will flow at a faster rate from the nozzle which is under the open place in the cloth; the air pressure will therefore drop in that sensing head to say one-third of a pound per square inch; the associated bellows will partially collapse; and the associated switch arm 84 will be moved to the left to cause associated electrical contact 87 to make contact with associated electrical contact 88, closing a circuit to the solenoid 93 which opens the circuit to the motor 107 of the machine and stops the machine.

The sensing head at the left hand side of the machine may be reversed with reference to the other sensing heads, as shown in Figs. 5 and 6, and, instead of being connected directly with the duct 28, may be connected with that duct by a nipple 96, a tube 97, a block 103, coupling 104, and tube 99. The tube 99 communicates with a duct, corresponding to the ducts 71 (Fig. 8) in the left hand sensing head 26. Nipple 96 is welded or otherwise fastened to the duct 28 with its bore 105 communicating through a port 106 with the duct 28. Tube 97 is connected at its right hand end to the nipple 96 so that its bore communicates with the bore 105 of the nipple. At its left hand end tube 97 is supported in block 103 which is mounted upon the duct 28. The coupling 104 is threaded into this block.

To adjust the nozzles 30 of the several sensing heads 26 into contact with the fabric, the supporting plate 70 is formed at its opposite ends with arms 110 (Figs. 3 and 4). Each of these arms has an arcuate slot 111 in it; and each arm is adapted to be supported by a right angular bracket 112 that is welded or otherwise secured to the frame of the machine. Bolts 113, which pass through the arcuate slots 111 and thread into the brackets 112, serve to secure the sensing heads in any angularly adjusted position.

Obviously, the bellows 80 can be used to break a circuit instead of closing one by attaching rod 82 to a switch arm so as to move that switch arm to open position on drop of pressure in the bellows. The switch shown in Fig. 7, therefore, is simply illustrative of one possibility of employment of the invention.

Instead of using a nut and a reversely-threaded screw to traverse the sensing heads across the fabric, any other suitable means may be employed for this purpose. For instance, as shown, in Fig. 12, the duct 28 might be traversed by a piston that reciprocates in a cylinder 121 and that is operated by fluid-pressure delivered to opposite sides of the piston alternately through pipes 122 and 123. The piston rod 124 is connected to the duct 28 by a lug 126 which is welded or otherwise secured to the duct. The right hand end of the piston rod 124 is threaded and passes through a hole in this lug and is held in engagement with this lug by nuts 127. In this case the compressed air for the sensing heads may be supplied to the right hand end of the duct 28 through a tube 128, but the electrical connections of the several switches with the actuating solenoid may be, as before, through wires 129 that enter the tube 28 at its right hand end. Othervent opening through a flaw in said fabric for stopping said machine.

3. A detector for a knitting machine comprising a chamber, a nozzle connected to said chamber, means ineluding an orifice for supplying compressed air to said nozzle and said chamber, said nozzle having a vent opening over which the fabric being formed in the machine is moved, said vent opening being larger than said orifice but being so small relative to the normal weave of the fabric that properly formed fabric passing over it will restrict escape of the compressed air from said chamber through said vent opening, and means operable upon escape of air from said chamber through said vent opening by reason of a flaw in the fabric for stopping the machine.

4. A detector for a knitting machine comprising a chamber, means for supplying compressed air to said chamber, a nozzle connected to said chamber, said nozzle having a vent opening over which the fabric formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrain escape of compressed air through said opening, and means operative upon change in pressure at said vent opening to stop said machine.

5. A detector for a knitting machine comprising a flexible chamber, means for supplying compressed air to said chamber, a nozzle connected to said chamber, said nozzle having a vent opening over which fabric formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrain escape of compressed air through said opening, and means connected to said chamber operable upon drop of pressure in said chamber to stop said machine.

6. A detector for a knitting machine comprising a fiexible chamber, means for supplying compressed air to said chamber, a nozzle connected to said chamber, said nozzle having a vent opening over which fabric formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrain escape of compressed air through said opening, and an electrical switch connected to said chamber to be operated by change of pressure in said chamber.

7. A detector for a knitting machine comprising a chamber, means including an orifice for supplying compressed air to said chamber, a nozzle connected to said chamber, said nozzle having a vent opening over which the fabric formed in the machine is moved, said vent opening being larger than said orifice but being so small relative to the normal knit of the fabric that properly formed fabric will restrict the rate of escape of air from said chamber through said opening, and a member movable upon escape of air at an increased rate from said chamber to stop said machine.

8. A detector for a knitting machine comprising a pair of chambers, means for supplying compressed air through an orifice to said chambers, a nozzle connected to one of said chambers, said nozzle having a vent opening over which the fabric formed in the machine is moved, said vent opening being larger than said orifice but being so small relative to the normal knit of the fabric that properly formed fabric will restrict the rate of escape of air from said chambers through said opening, electricallyoperated means for stopping said machine, and a member disposed between said chambers and movable by air escaping from said one chamber to close a circuit to said electrically-operated means.

9. A detector for a knitting machine comprising a pair of chambers, means for supplying compressed air through an orifice to said chambers, a nozzle connected to one of said chambers, a passage connecting the two chambers, said nozzle having a vent opening over which the fabric formed in the machine is moved, said opening being larger than said orifice but being so small relative to the normal knit of the fabric that properly formed fabric will restrict the rate of escape of air from said one chamher through said vent opening, a piston slidable in said passage and movable upon reduction of pressure in said one chamber, and means operable on movement of said piston to stop said machine.

10. A detector for a knitting machine comprising a pair of chambers, means for supplying compressed air through an orifice to said chambers, a nozzle connected to one of 8 said chambers, a passage connecting the two chambers, said nozzle having a vent opening over which the fabric formed in the machine is moved, said opening being larger than said orifice but being so small relative to the normal knit of the fabric that properly formed fabric will restrict the rate of escape of air from said one chamber through said opening, a piston slidable in said passage and movable in one direction by pressure of air in the other chamber upon increase in the rate of escape of air from said one chamber, said piston being electrically-conductive, and an electrical terminal member positioned to be engaged by said piston on movement of said piston in said one direction to establish an electrical circuit to stop said machine.

11. A detector for a knitting machine comprising a nozzle, said nozzle comprising a member having a diametral slot cut in it from one end thereof and open at said one end of said member and having a bore extending from the bottom of said slot toward the opposite end of said member, and a cap fitted over the slotted portion of said member and closing the diametrically opposite ends of said slot, the open end of said slot comprising the mouth of said nozzle over which the fabric formed in the machine is moved, and means for supplying compressed air to said bore.

12. A detector for a knitting machine comprising a. nozzle, said nozzle comprising a member having a diametral slot cut in it from one end thereof and open at said one end of said member and having a bore extending from the bottom of said slot toward the opposite end of said member, and a cap fitted over the slotted portion of said member and closing the diametrically opposite ends of said slot, the open end of said slot comprising the mouth of said nozzle over which the fabric formed in the machine is moved, and means for supplying compressed air to said bore, said slot being of tear-drop shape in cross-section and having its largest part at its bottom.

13. A detector for a knitting machine comprising a longitudinally reciprocable tube, and a plurality of sensing devices mounted on said tube in longitudinally-spaced relation to reciprocate with said tube, each of said sensing devices comprising a chamber communicating with the bore of said tube, and a nozzle connected to said chamber, means for supplying compressed air to said tube, and means for reciprocating said tube longitudinally to traverse the nozzles across the fabric, each nozzle having a vent opening over which the fabric formed in the machine is moved, said vent opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrict the rate of escape of compressed air through said opening, and means operable upon an increase in the rate of escape of the air through any one of said nozzles for stopping said machine.

14. A detector for a knitting machine comprising a longitudinally reciprocable tube, and a plurality of sensing devices mounted on said tube in longitudinally-spaced relation to reciprocate with said tube, each of said sensing devices comprising a chamber communicating with the bore of said tube, and a nozzle connected to said chamber, means for supplying compressed air to said tube, and means for reciprocating said tube longitudinally to traverse the nozzles across the fabric, each nozzle having a vent opening over which the fabric formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrict the rate of escape of compressed air through said opening, and means operable by change in pressure in any of said chambers for stopping said machine.

15. A detector for a knitting machine comprising a longitudinally reciprocable tube, and a plurality of sensing devices mounted on said tube in longitudinally-spaced relation to reciprocate with said tube, each of said sensing devices comprising a chamber communicating with the bore of said tube, and a nozzle connected to said chamber, means for supplying compressed air to said tube, and means for reciprocating said tube longitudinally to traverse the nozzles across the fabric, and means operable by change in pressure at any of said nozzles for stopping said machine.

16. A detector for a knitting machine comprising a longitudinally reciprocable tube, a plurality of sensing heads mounted on said tube in longitudinally spaced relation, each sensing head comprising a flexible bellows communicating with the bore of said tube, a nozzle connected to said bellows, and an electrical switch operable by expansion and contraction of said bellows, means for supplying compressed air to said tube, means for reciprocating said tube longitudinally to traverse the nozzles across the fabric, each nozzle having a vent opening over which the fabric formed in the machine is moved, said opening being so small widthwise of the fabric relative to the normal knit of the fabric that properly formed fabric passing over it will restrict the rate of escape of compressed air through said opening, and means operable by increase in the rate of escape of air tllilrough any one of said nozzles for stopping said mac me.

17. A detector for a knitting machine comprising a longitudinally reciprocable tube, a plurality of sensing heads mounted on said tube in longitudinally spaced relation, each sensing head comprising a tubular chamber closed at one end, a nozzle, a block closing the other end of said chamber, each block having an orifice formed therein and having a passage connecting the bore of said tube with said chamber, and having a second duct formed therein connecting said passage to said nozzle, and a piston reciprocable in said passage and disposed between the nozzle and said chamber, means for supplying compressed air to said tube, and means for reciprocating said tube longitudinally to traverse the nozzles across the fabric, each nozzle having a vent opening over which the fabric formed in the machine is moved, said vent opening being larger than'the orifice in the associated block and being so small widthwise of the fabric relative to the normal knit of the fabric that properly formed fabric passing it will restrict the rate of escape of compressed air through said vent opening, and each piston being movable by the pressure in the associated chamber upon increase in the rate of escape of air from the associated vent opening to stop said machine.

18. A detector for a knitting machine comprising chamber, means for supplying compressed air through an orifice to said chamber, a nozzle connected to said chamber, said nozzle having a vent opening over which fabric formed on the machine is moved, said opening being larger than said orifice but being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrict the rate of escape of compressed air through said opening, and means operable upon reduction in pressure in said chamber to stop said machine.

19. A detector for a knitting machine comprising means tending to move air through the interstices of the fabric being formed in the machine, said means including an air-conducting sensing member having an opening over which the fabric being formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrict passage of air through said member, and means connected to the first-named means operative on increase in rate of passage of air through the said fabric by reason of a flaw in the fabric for stopping said machine.

20. A detector for a knitting machine comprising means tending to move air through the interstices of the fabric being formed in the machine, said means including a member adapted to be disposed in contiguity to said fabric, and having an opening over which the fabric being formed in the machine is moved, said opening being so small relative to the normal knit of the fabric that properly formed fabric passing over it will restrain movement of air through the fabric, and an electrical switch connected to said means to be operated upon increase in rate of passage of air through the fabric by reason of a flaw in the fabric.

Name Date Rosenstein Apr. 22. 1952 Number 

